Late to the party, but I'm with the majority. For me, it basically comes down to 'Can the Power Stone hurt Thanos?' Because MCU Thanos without the Gauntlet doesn't have an energy projection powers or ranged attacks. He needs to GET to Ronan to try to hit him.

Ronan doesn't really have a lot to show he can manage to outfight Thanos in close, but he doesn't need to - if the Power Stone has the oomph to mess up Thanos, then the big purple guy is never reaching the big blue guy. Ronan showed enough instances of being able to hit areas with attacks that sent everyone flying to tell me he's not going to have a hard time stopping the non-superspeed Thanos from getting close.

Which means he's going to have plenty of time to deploy some kind of powerful attack from the power stone. And if it has the stuff to take out Thanos, then that's all she wrote.

Given that Ronan's hammer with the stone supposedly can essentially kill a planet, I'm pretty cool with him having the capacity to take this one, myself. Mileage, varies, etc.